دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: See bumper sub.

n: a device made up in the drill string that, when actuated, de- livers a heavy downward blow to the string. A bumper jar has a hollow body that moves upward when the drill string is picked up. When the string is dropped quickly, the jar body produces a sharp downward blow on the tubing or pipe made up below the jar. If downward blows can free a fish, a bumper jar can be very effective.

n: Made by upwardness, lower part of the body and joint. The upwardness and lower part of the body are connected with plain bearing. The operating principle of it is the same with bumper sub. Used to handle sticking when the drill bit is not at the bottom.

n: a percussion tool run on a fishing string to jar downward or upward on a stuck fish to knock it free. The bumper sub body moves up and down on a mandrel.

n: A drilling tool consisting of a short stroke slip joint that allows a more constant WOB when drilling from a floating rig.

n: refer to drilling jar

n: refer tofishing jar

n: a device that moves with the heave of a floating offshore drilling rig to prevent the bit from being lifted off the bottom of the hole and then dropped back down (i.e., to maintain constant weight on the bit). It is used with devices such as bumper subs. See motion compensator.

n: a percussion tool operated manually or hydraulically to deliver a heavy downward blow to fish stuck in the borehole. v: to apply a heavy blow to the drill stem by use of a jar or bumper sub.

n: a downhole tool used to deliver an impact force either up or down to the tool string, usually to operate downhole tools or to dislodge a stuck tool string. Jars of different designs and operating priciples are commonly included on slickline,coiled tubing,

a device run on slickline, coiled tubing, tubing or drill pipe that will sharply increase the impact force of the conveyance when trying to retrieve a stuck tool or equipment.

n: a device used to ream out a hole where keyseating has occurred. Usually a bumper sub is used first to loosen stuck pipe from a sharp bend, and then a keyseat wiper is used to enlarge the hole at the keyseat caused by the pipe. Also called

n: a tool made up in the drill string to ream out any keyseats that may have formed and thus prevent the pipe from becoming struck.

n: any device (such as a bumper sub or heave compensator) that serves to maintain constant weight on the bit in spite of vertical motion of a floating offshore drilling rig.